The Molecules of HIV
Cellular proteins are incorporated into HIV particles
www.mcld.co.uk/hiv
Most of the work on HIV so far has considered HIV's "own" proteins. This is understandable; but did you know that when a HIV particle buds off from a host cell, it also takes lots of proteins with it from the host cell?
HLA-DR
The most common inclusion is HLA protein, which is cell-surface protein involved in the human immune system. There are various varieties of HLA produced by cells in the human body, but most commonly, HIV incorporates HLA-DR.
It's often hard for researchers to tell, if they find a cellular protein in HIV particles, whether it's there "on purpose" or "by accident". But the quantities of HLA-DR are too large for it to be an accident, so something must be going on here. Why would HIV drag other proteins into the budding virus particle? Does it mean that these other proteins are important to the mechanism of HIV infection?
The answer, for HLA-DR at least, seems to be yes. Viruses with no HLA-DR are slightly less infectious; and there's evidence that the HLA-DR also affects how deadly the virus is to T-cells.
Others
HLA-DR is a cell-surface protein, so it acts like a cell-surface protein in HIV, sticking out of the lipid bilayer just like the env spikes do. Other cell-surface proteins that have been found incorporated into HIV include HLA class I, and various cell adhesion proteins (proteins which help cells stick to each other).
And it's not just cell-surface proteins! Proteins that normally sit inside cells, such as cyclophilin A, actin, and ubiquitin have been found in HIV particles.
More information:
- Ott, D.E. (1997) Cellular Proteins in HIV Virions. Reviews in Medical Virology 7: 167-180
Written by
Dan Stowell
(©2002-2006)
